1. Field of the Invention
The present invention relates to a transmitter/receiver (T/R) switch and in particular to an integrated T/R switch that minimizes components and silicon area.
2. Related Art
Increasing consumer demand for a smaller and cheaper wireless device drives technology developments in the device's constituent components to achieve the desired size and cost reductions. For example, to reduce the size and cost of a transmit/receive (T/R) switch in a transceiver, manufacturers have attempted to integrate this T/R switch onto a single low cost integrated circuit. Unfortunately, such an “integrated” T/R switch may cause performance issues that offset the benefits of size and cost reductions.
Exemplary integrated T/R switches have used simple MOSFETS to implement the transmitter and receiver switches. Unfortunately, using MOSFETs to implement a standard configuration T/R switch can only work well for low power circuits. Specifically, a standard MOSFET T/R switch cannot handle large output swings from the power amplifier. Therefore, if the power amplifier uses a high supply voltage, then the MOSFET T/R switch needs to be high voltage as well. Unfortunately, this high voltage T/R MOSFET switch can cause a large, undesirable loss in at least one of the transmit and receive functions.
In an article entitled, “Integrated CMOS Transmit-Receive Switch Using LC-Tuned Substrate Bias for 2.4 GHz and 5.2-GHz Applications,” IEEE Journal of Solid-State Circuits, Vol. 39, No. 6, June 2004, p. 863-870, N. Talwalkar et al. describe an integrated T/R switch that overcomes high voltage stress by using two additional inductors and a large isolation region around one of the MOSFET switches. This configuration overcomes the loss and reliability issues associated with simple MOSFET switches, but at the expense of considerable additional silicon area (e.g. on the order of one sq. mm.).
Therefore, a need arises for an integrated T/R switch that minimizes components and silicon area without sacrificing performance.